E-Antenna Near Field Transducer With Thermal Shunt To Return Pole

ABSTRACT

In a heat-assisted magnetic recording head for use in a hard disk drive, a thermal shunt is positioned between an E-antenna near field transducer (NFT) and a return pole, to draw excess heat away from the NFT region. The thermal shunt comprises two portions separated by a gap that has a trapezoidal cross-section, where the NFT-side of the gap is wider than the return pole-side of the gap.

FIELD OF EMBODIMENTS OF THE INVENTION

Embodiments of the invention relate generally to hard disk drives andmore particularly to thermal management in a heat-assisted magneticrecording head.

BACKGROUND

A hard-disk drive (HDD) is a non-volatile storage device that is housedin a protective enclosure and stores digitally encoded data on one ormore circular disks having magnetic surfaces. When an HDD is inoperation, each magnetic-recording disk is rapidly rotated by a spindlesystem. Data is read from and written to a magnetic-recording disk usinga read/write head that is positioned over a specific location of a diskby an actuator. A read/write head uses a magnetic field to read datafrom and write data to the surface of a magnetic-recording disk.

Increasing areal density (a measure of the quantity of information bitsthat can be stored on a given area of disk surface) is one of theever-present holy grails of hard disk drive design evolution, and hasled to the necessary development and implementation of various means forreducing the disk area needed to record a bit of information. It hasbeen recognized that one significant challenge with minimizing bit sizeis based on the limitations imposed by the superparamagnetic effectwhereby, in sufficiently small nanoparticles, the magnetization canrandomly flip direction under the influence of thermal fluctuations.

Heat-assisted magnetic recording (HAMR) [which may also be referred toas energy-assisted magnetic recording (EAMR) or thermal-assistedmagnetic recording (TAR)] is a known technology that magneticallyrecords data on high-stability media using, for example, laser thermalassistance to first heat the media material. HAMR takes advantage ofhigh-stability, high coercivity magnetic compounds, such as ironplatinum alloy, which can store single bits in a much smaller areawithout being limited by the same superparamagnetic effect that limitsthe current technology used in hard disk drive storage. However, at somecapacity point the bit size is so small and the coercivitycorrespondingly so high that the magnetic field used for writing datacannot be made strong enough to permanently affect the data and data canno longer be written to the disk. HAMR solves this problem bytemporarily and locally changing the coercivity of the magnetic storagemedium by raising the temperature above the Curie temperature, at whichthe medium effectively loses coercivity and a realistically achievablemagnetic write field can write data to the medium.

One approach to HAMR designs is to utilize a semiconductor laser systemto heat the media to lower its coercivity, whereby the optical energy istransported from the laser to the slider ABS via a waveguide and isconcentrated to a nanometer-sized spot utilizing a near field transducer(NFT). However, some of the optical energy provided to the NFT isabsorbed by the materials in and surrounding the NFT. Consequently,heat-induced degradation of the NFT as well as the write pole lip mayoccur and, ultimately, possible head failure.

More detailed information about the structure and functionality of athermally assisted magnetic write head employing an NFT can be found inU.S. Pat. No. 8,351,151 to Katine et al., which is incorporated byreference in its entirety for all purposes as if fully set forth herein.

SUMMARY OF EMBODIMENTS OF THE INVENTION

Embodiments of the invention are directed towards a near fieldtransducer with a thermal shunt, in a heat-assisted magnetic recordinghead for use in a hard disk drive.

According to an embodiment, a thermal shunt is positioned between anE-antenna near field transducer (NFT) and a return pole, to draw excessheat away from the NFT and to provide surface area for convection ofheat away from the head slider surface. According to an embodiment, thethermal shunt comprises two portions separated by, for example, alumina.According to an embodiment, the gap between the two portions of thethermal shunt has a trapezoidal cross-section, where the NFT-side of thegap is wider than the return pole-side of the gap.

Embodiments discussed in the Summary of Embodiments of the Inventionsection are not meant to suggest, describe, or teach all the embodimentsdiscussed herein. Thus, embodiments of the invention may containadditional or different features than those discussed in this section.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are illustrated by way of example, and notby way of limitation, in the figures of the accompanying drawings and inwhich like reference numerals refer to similar elements and in which:

FIG. 1 is a plan view illustrating an HDD, according to an embodiment ofthe invention;

FIG. 2 is an air bearing surface view illustrating a conventional nearfield transducer configuration for a heat-assisted magnetic recordinghead;

FIG. 3 is an air bearing surface view illustrating a near fieldtransducer configuration with a thermal shunt, according to anembodiment of the invention; and

FIG. 4 is a bottom view illustrating the NFT-to-shunt interface,according to an embodiment of the invention.

DETAILED DESCRIPTION

Approaches for a heat-assisted magnetic recording head having a nearfield transducer with a thermal shunt, for use in a hard disk drive forexample, are described. In the following description, for the purposesof explanation, numerous specific details are set forth in order toprovide a thorough understanding of the embodiments of the inventiondescribed herein. It will be apparent, however, that the embodiments ofthe invention described herein may be practiced without these specificdetails. In other instances, well-known structures and devices are shownin block diagram form in order to avoid unnecessarily obscuring theembodiments of the invention described herein.

Physical Description of Illustrative Embodiments of the Invention

Embodiments of the invention may be used in the context of a magneticwriter for a hard-disk drive (HDD). In accordance with an embodiment ofthe invention, a plan view illustrating an HDD 100 is shown in FIG. 1.FIG. 1 illustrates the functional arrangement of components of the HDDincluding a slider 110 b that includes a magnetic-reading/recording head110 a. Collectively, slider 110 b and head 110 a may be referred to as ahead slider. The HDD 100 includes at least one head gimbal assembly(HGA) 110 including the head slider, a lead suspension 110 c attached tothe head slider, and a load beam 110 d attached to the lead suspension110 c. The HDD 100 also includes at least one magnetic-recording media120 rotatably mounted on a spindle 124 and a drive motor (not shown)attached to the spindle 124 for rotating the media 120. The head 110 aincludes a write element and a read element for respectively writing andreading information stored on the media 120 of the HDD 100. The media120 or a plurality (not shown) of disks may be affixed to the spindle124 with a disk clamp 128.

The HDD 100 further includes an arm 132 attached to the HGA 110, acarriage 134, a voice-coil motor (VCM) that includes an armature 136including a voice coil 140 attached to the carriage 134; and a stator144 including a voice-coil magnet (not shown). The armature 136 of theVCM is attached to the carriage 134 and is configured to move the arm132 and the HGA 110 to access portions of the media 120 being mounted ona pivot-shaft 148 with an interposed pivot-bearing assembly 152. In thecase of an HDD having multiple disks, or platters as disks are sometimesreferred to in the art, the carriage 134 is called an “E-block,” orcomb, because the carriage is arranged to carry a ganged array of armsthat gives it the appearance of a comb.

With further reference to FIG. 1, in accordance with an embodiment ofthe present invention, electrical signals, for example, current to thevoice coil 140 of the VCM, write signal to and read signal from the head110 a, are provided by a flexible interconnect cable 156 (“flex cable”).Interconnection between the flex cable 156 and the head 110 a may beprovided by an arm-electronics (AE) module 160, which may have anon-board pre-amplifier for the read signal, as well as otherread-channel and write-channel electronic components. The AE 160 may beattached to the carriage 134 as shown. The flex cable 156 is coupled toan electrical-connector block 164, which provides electricalcommunication through electrical feedthroughs (not shown) provided by anHDD housing 168. The HDD housing 168, also referred to as a casting,depending upon whether the HDD housing is cast, in conjunction with anHDD cover (not shown) provides a sealed, protective enclosure for theinformation storage components of the HDD 100.

With further reference to FIG. 1, in accordance with an embodiment ofthe present invention, other electronic components (not shown),including a disk controller and servo electronics including adigital-signal processor (DSP), provide electrical signals to the drivemotor, the voice coil 140 of the VCM and the head 110 a of the HGA 110.The electrical signal provided to the drive motor enables the drivemotor to spin providing a torque to the spindle 124 which is in turntransmitted to the media 120 that is affixed to the spindle 124 by thedisk clamp 128; as a result, the media 120 spins in a direction 172. Thespinning media 120 creates a cushion of air that acts as an air-bearingon which the air-bearing surface (ABS) of the slider 110 b rides so thatthe slider 110 b flies above the surface of the media 120 without makingcontact with a thin magnetic-recording medium in which information isrecorded.

The electrical signal provided to the voice coil 140 of the VCM enablesthe head 110 a of the HGA 110 to access a track 176 on which informationis recorded. Thus, the armature 136 of the VCM swings through an arc 180which enables the HGA 110 attached to the armature 136 by the arm 132 toaccess various tracks on the media 120. Information is stored on themedia 120 in a plurality of stacked tracks (not shown) arranged insectors on the media 120, for example, sector 184. Correspondingly, eachtrack is composed of a plurality of sectored track portions, forexample, sectored track portion 188. Each sectored track portion 188 iscomposed of recorded data and a header containing a servo-burst-signalpattern, for example, an ABCD-servo-burst-signal pattern, informationthat identifies the track 176, and error correction code information. Inaccessing the track 176, the read element of the head 110 a of the HGA110 reads the servo-burst-signal pattern which provides aposition-error-signal (PES) to the servo electronics, which controls theelectrical signal provided to the voice coil 140 of the VCM, enablingthe head 110 a to follow the track 176. Upon finding the track 176 andidentifying a particular sectored track portion 188, the head 110 aeither reads data from the track 176 or writes data to the track 176depending on instructions received by the disk controller from anexternal agent, for example, a microprocessor of a computer system.

Heat-Assisted Magnetic Recording Head

FIG. 2 is an air bearing surface (ABS) view illustrating a conventionalnear field transducer configuration for a heat-assisted magneticrecording head, according to an embodiment of the invention. Withreference to FIG. 2, a heat-assisted magnetic recording (HAMR) head 200is described, which may be incorporated into a head such as head 110 a(FIG. 1). The HAMR head comprises a write pole 202 and a magnetic returnpole that both extend to the ABS. The write pole 202 may comprise awrite pole lip 203, and the return pole may comprise a return polepedestal 204, both also at the ABS. As depicted, the return polepedestal 204 has a cross section at the ABS that is larger than thecross section of the write pole 202 at the ABS. The write pole 202 canbe connected with a shaping layer in a region removed from the ABS. Amagnetic back gap layer connects the shaping layer with the return polein a region removed from the ABS, thereby magnetically connecting thewrite pole 202 with the return pole and shaping layer in a regionremoved from the ABS. The write pole 202, the return pole pedestal 204,shaping layer and back gap are all constructed of a magnetic material,such as CoNiFe, NiFe or CoFe.

In view of the head being a HAMR head, the HAMR head 200 comprises aheating assembly that can be provided adjacent to the write pole 202 forlocally heating the magnetic media 120 (FIG. 1). For example, aplasmonic heating device may be implemented for the heating assembly.Thus, according to an embodiment, the heating assembly comprises anoptical energy source, such as a semiconductor laser mounted on or nearthe backside (opposite the ABS) of the head slider. The heating assemblyfurther comprises a near-field transducer (NFT) 206 for concentratingthe optical energy to a nanometer-sized spot to locally heat themagnetic media 120 in a region just upstream from the write pole 202.Further, the heating assembly comprises a waveguide to guide, transmitor carry the optical energy to the ABS, to illuminate the NFT 206.

This localized heating of the magnetic media 120 (FIG. 1) momentarilyreduces the local coercivity of the magnetic media 120, which greatlyfacilitates writing to a magnetic media 120 which has an otherwise toohigh coercivity to be written to. In order for the heating assembly tofunction effectively, it should be located as close as possible to thewrite pole 202. In addition, the heating assembly should heat only avery small area on the media in order to avoid demagnetizing adjacenttracks of data or downstream data on the same track.

According to an embodiment, the NFT 206 comprises an E-antenna (orc-aperture). The dielectric aperture in such a structure looks like theletter “c”, while the metal surrounding that dielectric forms an antennain the shape of a capital letter “E”. As such, the HAMR head 200comprises an aperture 208 and the E-antenna NFT 206 comprises a tip 207,whose dimensions in part determine the near-field spot size, i.e., thesize of the localized heating of the magnetic media 120 (FIG. 1). Theelectrical interaction of the write pole 202 and the NFT 206 form whatis referred to as an LC resonator (or “LC circuit”), whereby anelectrical field oscillates between the write pole lip 203 and the NFTtip 207, thereby interacting optically with and generating heat in themagnetic media 120 by generating AC currents (at optical frequencies)within the magnetic media 120, which in turn are responsible for heatgeneration in the media itself through Joule heating. In operation, theE-antenna NFT 206 generates heat not only at the media but also at theNFT 206. Therefore, it is typical to provide a heat sink structure, suchas a heat sink 210 and the lateral “wings” of NFT 206 outside the writepole lip 203-NFT tip 207-aperture 208 area, to direct some of the heataway from the write pole lip 203 and NFT tip 207 (such as depicted byblock arrows 211), for convection away from the slider at the ABS.However, note that in a conventional E-antenna NFT configuration, suchas illustrated in FIG. 2, a large gap (˜400 nm) separates the bottom ofthe NFT and the return pole pedestal.

Certain approaches to fabricating a c-aperture or E-antenna plasmonicNFT are described in U.S. Pat. No. 8,092,704 to Balamane et al., thesubject matter of which is incorporated by reference for all purposes asif fully set forth herein.

Heat-Assisted Magnetic Recording Head with Thermal Shunt to Return Pole

A portion of the optical power not converted into the focused opticalpower generates heat at the NFT 206 and the surrounding region. Thus,the aforementioned concentration of light energy leads to heating of theE-antenna NFT 206, and the write pole lip 203, for example. The excessheat at the NFT 206 causes it to degrade over time, for example, thegold with which the E-antenna is typically fabricated may buckle.

FIG. 3 is an air bearing surface view illustrating a near fieldtransducer configuration with a thermal shunt, according to anembodiment of the invention. Similar to the HAMR head 200 illustrated inand described in reference to FIG. 2, the HAMR head 300 of FIG. 3comprises a write pole 302 and a magnetic return pole that both extendto the ABS. The write pole 302 may comprise a write pole lip 303, andthe return pole may comprise a return pole pedestal 304, both also atthe ABS. The write pole 302 can be connected with a shaping layer in aregion removed from the ABS. A magnetic back gap layer connects theshaping layer with the return pole in a region removed from the ABS,thereby magnetically connecting the write pole 302 with the return poleand shaping layer in a region removed from the ABS. The write pole 302,the return pole pedestal 304, shaping layer and back gap are allconstructed of a magnetic material, such as CoNiFe, NiFe or CoFe.

In view of the head being a HAMR head, the HAMR head 300 comprises aheating assembly that can be provided adjacent to the write pole 302 forlocally heating the magnetic media 120 (FIG. 1). For example, aplasmonic heating device may be implemented for the heating assembly.Thus, according to an embodiment, the heating assembly comprises anoptical energy source, such as a semiconductor laser (e.g., a laserdiode) mounted on or near the backside (opposite the ABS) of the headslider. The heating assembly further comprises a near-field transducer(NFT) 306 for concentrating the optical energy to a nanometer-sized spotto locally heat the magnetic media 120 in a region just upstream fromthe write pole 302. Further, the heating assembly comprises a waveguideto guide, transmit or carry the optical energy to the ABS, to illuminatethe NFT 306.

According to an embodiment, the NFT 306 comprises an E-antenna (orc-aperture), similar to or the same as described with reference to FIG.2. As such, the HAMR head 300 comprises an aperture 308 and theE-antenna NFT 306 comprises a tip 307, whose dimensions in partdetermine the near-field spot size, i.e., the size of the localizedheating of the magnetic media 120 (FIG. 1). The electrical interactionof the write pole 302 and the NFT 306 form what is referred to as an LCresonator (or “LC circuit”), whereby an electrical field oscillatesbetween the write pole lip 303 and the NFT tip 307, thereby interactingoptically with and generating heat in the magnetic media 120 bygenerating AC currents (at optical frequencies) within the magneticmedia 120, which in turn are responsible for heat generation in themedia itself through Joule heating.

According to an embodiment, the mode associated with the polarization ofthe illumination, i.e., the electromagnetic radiation, used to heat themagnetic media 120 is a transverse magnetic (TM) mode, in which there isno magnetic field in the direction of propagation of the electromagneticradiation. This TM mode is in contrast with a transverse electric (TE)mode, in which there is no electric field in the direction ofpropagation of the electromagnetic radiation. The mode in which thesystem operates is related to the position at which the energy source iscoupled to the head slider, and affects the manner in which the NFToperates. As discussed, the E-antenna NFT 306 operates in a TM mode,where the electrical field resonates between the write pole lip 303 andthe NFT tip 307.

In operation, the E-antenna NFT 206 generates heat not only at the mediabut also at the NFT 206. Therefore, it is beneficial to provide one ormore heat sink structures, such as a heat sink 310 as well as thelateral “wings” of NFT 306 outside the immediate write pole lip 303-NFTtip 307-aperture 308 region, to direct some of the heat away from thisregion. Airflow and convection at the ABS is the primary mechanism fordissipating heat from the slider, generally, and the NFT 306 area inparticular.

An E-antenna type of NFT is unique among other types of NFT's for HAMRin that the E-antenna NFT can tolerate the presence of metal heat sinksin the vicinity of the field enhancement region without this resultingin adverse effects on optical performance. Therefore, HAMR head 300further comprises a thermal shunt 312 positioned between the NFT 306 andthe return pole pedestal 304, according to an embodiment. Thermal shunt312 acts to direct more of the excess heat away from the write pole lip303 and NFT tip 307 (such as depicted by block arrows 311) in part bydiffusing the heat across more surface area of the ABS so that moreconvection may occur. Thermal shunt 312 of HAMR head 300 effectivelyprovides an additional path for heat to escape from the NFT 306 area, incomparison with the HAMR head 200. With thermal shunt 312 the excessheat is now also directed toward the return pole pedestal 304, forconvection away from the slider. Introducing a thermal shunt heat sinkbetween the NFT 306 and the return pole pedestal 304 is an effective wayto reduce the NFT tip 307 and write pole lip 303 temperature of a givenE-antenna structure with a fixed magnetic lip width and a fixedlip-to-tip spacing.

According to an embodiment, thermal shunt 312 is a multi-piecestructure, for example, having two portions which are separated fromeach other in a lateral (cross-track) direction. Therefore, according toan embodiment, thermal shunt 312 comprises a first portion 312 a and asecond portion 312 b, which are separated by a gap 313. The gap 313 maybe filled with a dielectric, such as alumina (Al₂O₃) or silica (SiO₂) orsome other dielectric with relatively similar optical properties. Forheat diffusion purposes alone, a single-piece, continuous heat sink maybe more beneficial than a multi-piece thermal shunt such as thermalshunt 312. However, a single-piece thermal shunt would break theresonance of the LC resonator embodied by the electrical interaction ofthe write pole 302 and the NFT 306, by altering the values of thecapacitor (C) and/or the inductor (L) elements, as the thickness(height) of the metal of NFT 306 beneath the aperture 308 has asignificant effect on the resonance of the LC resonator functionality.If thermal shunt 312 were a continuous piece of metal between the NFT306 and the return pole pedestal 304, then the electrical field betweenthe write pole lip 303 and NFT tip 307 would be weakened which would inturn diminish the amount of heat that can be generated by thestructures. Furthermore, if one were to mirror the E-antenna (with orwithout a tip) below NFT 306, thereby forming what is referred to as anH-antenna, two separate hot spots would be generated. This is anundesirable scenario as the additional hot spot would likely eraseadjacent tracks on the magnetic media when the H-antenna is operating.

Research has shown that use of an optimized thermal shunt between theNFT and the return pole pedestal, such as thermal shunt 312 between NFT306 and pedestal 304 as described herein, can reduce the peak NFTtemperature rise by up to approximately 24%.

Thermal Shunt Configuration Considerations

The precise dimensions associated with portions 312 a, 312 b of thermalshunt 312 may vary from implementation to implementation based on, forexample, the corresponding configurations of the NFT and other HAMR headstructures. Some general guidance in this regard is as follows.

With further reference to FIG. 3, the gap 313 between the first portion312 a and the second portion 312 b of thermal shunt 312 is depicted ashaving a trapezoidal shape, where the distance between the uppersurfaces (the NFT-sides) of portions 312 a, 312 b is greater than thedistance between the lower surfaces (the return-pole sides) of portions312 a, 312 b. Such a trapezoidal shape is effective and is preferablebased on several considerations. Regarding the distance between theNFT-sides of portions 312 a, 312 b, this distance should be sufficientlywide enough so that it does not alter the LC values, sufficiently narrowenough so that it effectuates the dissipation of the heat from the NFTstructures effectively, and that it accounts for manufacturing andalignment tolerances.

As discussed, a single-piece thermal shunt would break the resonance ofthe LC resonator embodied by the electrical interaction of the writepole 302 and the NFT 306. Similarly, a two-piece thermal shunt havingNFT-sides that are too close together would also affect the electricalfield of the LC resonator and the corresponding heat generatedtherefrom. Regarding the distance between the return pole-sides ofportions 312 a, 312 b, this distance should be sufficiently wide enoughso that it does not create an undesirably large hot spot, or additionalhot spots at the interface between the return pole-sides and the returnpole pedestal 304. The closer together are the return pole-sides ofportions 312 a and 312 b the more likely that a secondary strong opticalfield may develop near where the return pole-sides are converging andconsequently the more likely that this secondary strong optical fieldwould interact with the media to generate a secondary hot spot in themedia through Joule heating, such as would likely occur if the returnpole-sides of portions 312 a and 312 b are in contact with each other.Thus, modeling has shown that a preferred, but not limiting, angle ofincline (a) between the NFT-side and the corresponding return pole-sidefor each of portions 312 a and 312 b should not exceed approximately 30degrees from the vertical, to avoid creation of secondary hot spots.

The thermal shunt 312 is a three-dimensional structure that follows thecross-track and throat profile of the NFT 306, according to anembodiment. FIG. 4 is a bottom view illustrating the NFT-to-shuntinterface, slicing through HAMR head 300 at interface line A-A of FIG.3, according to an embodiment of the invention. FIG. 4 illustrates thetop of the first portion 312 a and the second portion 312 b of thermalshunt 312, which is positioned below NFT 306, a bottom portion of whichis viewable extending outside of the boundaries of the first and secondportions 312 a, 312 b. In this bottom view, the ABS is toward the top ofthe drawing of FIG. 4.

Dimension a represents the operational width of NFT 306, i.e., anoptimized width necessary for its proper operational functionality.Dimension b and dimension c represent optimized dimensions determined toaccount for nominal lateral (left-right, in this illustration)fabrication misalignment of the thermal shunt portions 312 a, 312 brelative to the NFT 306, such that the thermal shunt 312 does notinterfere with the optical operation of NFT 306. Typically, dimension band dimension c would be equal due to equivalent nominal fabricationtolerances present on each side of the operational width of NFT 306.Similarly, dimension d represents an optimized dimension determined toaccount for nominal longitudinal (up-down, in this illustration)fabrication misalignment of the thermal shunt portions 312 a, 312 brelative to the NFT 306, such that the thermal shunt 312 does notinterfere with the optical operation of NFT 306.

According to an embodiment and as depicted in FIG. 4, thermal shunt 306is configured as wide as the NFT 306, which includes the operationalwidth and its lateral “wing” heat sink structures. As such, the presenceof the thermal shunt 312 does not significantly alter the power radiatedby the waveguide at the dielectric aperture 308 (FIG. 3) at the NFT 306to the far-field. This far-field power signal can be used for alignmentof the semiconductor laser to the slider during manufacturing. Further,according to an alternative embodiment, the thermal shunt 312cross-track dimension (width) is extended to the full width of thereturn pole pedestal 304, to block any stray light that was not properlycoupled form the laser to the dielectric waveguide. This stray light isundesirable because it pollutes the aforementioned far-field powersignal that can be relied on to accurately perform the laser-to-slideralignment process.

In the foregoing specification, embodiments of the invention have beendescribed with reference to numerous specific details that may vary fromimplementation to implementation. Thus, the sole and exclusive indicatorof what is the invention, and is intended by the applicants to be theinvention, is the set of claims that issue from this application, in thespecific form in which such claims issue, including any subsequentcorrection. Any definitions expressly set forth herein for termscontained in such claims shall govern the meaning of such terms as usedin the claims. Hence, no limitation, element, property, feature,advantage or attribute that is not expressly recited in a claim shouldlimit the scope of such claim in any way. The specification and drawingsare, accordingly, to be regarded in an illustrative rather than arestrictive sense.

1. A heat-assisted magnetic recording (HAMR) head slider comprising: a magnetic write pole extending to an air bearing surface; a magnetic return pole, magnetically connected with said write pole in a region removed from said air bearing surface; an E-antenna near field transducer (NFT) configured to receive optical energy and to emit at least a portion of said optical energy to a magnetic-recording medium, said NFT comprising an E-antenna, an aperture, and a magnetic write pole lip; and a thermal shunt positioned between said NFT and said return pole and configured to draw heat from said NFT, said thermal shunt comprising a first portion and a second portion separated from said first portion.
 2. (canceled)
 3. The HAMR head slider of claim 1, wherein said first portion comprises an NFT-side and a return pole-side and said second portion comprises an NFT-side and a return pole-side, and wherein the distance between said NFT-sides is greater than the distance between said return-pole sides.
 4. The HAMR head slider of claim 1, wherein said thermal shunt comprises a first portion and a second portion separated from said first portion by a trapezoidal cross-section shaped gap.
 5. The HAMR head slider of claim 1, wherein said thermal shunt comprises a first portion and a second portion separated from said first portion by a dielectric gap.
 6. The HAMR head slider of claim 1, wherein said write pole lip and said E-antenna form an LC resonator.
 7. The HAMR head slider of claim 1, wherein said optical energy received at said E-antenna NFT has a transverse magnetic mode of electromagnetic radiation.
 8. The HAMR head slider of claim 1, wherein said E-antenna NFT has a particular lateral width at said air bearing surface, and wherein said thermal shunt has a lateral width approximate to said particular lateral width of said E-antenna NFT.
 9. The HAMR head slider of claim 1, wherein said return pole comprises a pedestal having a particular lateral width at said air bearing surface, and wherein said thermal shunt has a lateral width approximate to said particular lateral width of said return pole pedestal.
 10. A hard disk drive, comprising: a heat-assisted magnetic recording (HAMR) head slider comprising: a magnetic write pole extending to an air bearing surface, a magnetic return pole, magnetically connected with said write pole in a region removed from said air bearing surface, an E-antenna near field transducer (NFT) configured to receive optical energy and to emit at least a portion of said optical energy to a magnetic-recording medium, said NFT comprising an E-antenna, an aperture, and a magnetic write pole lip, and a thermal shunt positioned between said NFT and said return pole and configured to draw heat from said NFT, said thermal shunt comprising a first portion and a second portion separated from said first portion; a magnetic-recording disk rotatably mounted on a spindle; a voice coil motor configured to move said head slider to access portions of said magnetic-recording disk.
 11. (canceled)
 12. The hard disk drive of claim 10, wherein said first portion comprises an NFT-side and a return pole-side and said second portion comprises an NFT-side and a return pole-side, and wherein the distance between said NFT-sides is greater than the distance between said return-pole sides.
 13. The hard disk drive of claim 10, wherein said thermal shunt comprises a first portion and a second portion separated from said first portion by a trapezoidal cross-section shaped gap.
 14. The hard disk drive of claim 10, wherein said thermal shunt comprises a first portion and a second portion separated from said first portion by a dielectric gap.
 15. The hard disk drive of claim 10, wherein said write pole lip and said E-antenna form an LC resonator.
 16. The hard disk drive of claim 10, wherein said optical energy received at said E-antenna NFT has a transverse magnetic mode of electromagnetic radiation.
 17. The hard disk drive of claim 10, wherein said E-antenna NFT has a particular lateral width at said air bearing surface, and wherein said thermal shunt has a lateral width approximate to said particular lateral width of said E-antenna NFT.
 18. The hard disk drive of claim 10, wherein said return pole comprises a pedestal having a particular lateral width at said air bearing surface, and wherein said thermal shunt has a lateral width approximate to said particular lateral width of said return pole pedestal.
 19. A heat-assisted magnetic recording (HAMR) head slider comprising: a magnetic write pole extending to an air bearing surface and having a write pole lip; a magnetic return pole, magnetically connected with said write pole in a region removed from said air bearing surface and having a return pole pedestal at said air bearing surface; a near field transducer (NFT) configured to receive optical energy and to emit at least a portion of said optical energy to a magnetic-recording medium, said NFT comprising an E-antenna having a tip, a lateral heat sink on each side of said E-antenna, an aperture, and said write pole lip; and a thermal shunt positioned between said NFT and said return pole pedestal and configured to draw heat from a region around said NFT, said thermal shunt comprising a first portion and a second portion separated from said first portion by a trapezoidal cross-section shaped gap.
 20. The HAMR head slider of claim 19, wherein said NFT has a particular lateral width at said air bearing surface, and wherein said thermal shunt has a lateral width approximate to said particular lateral width of said NFT. 